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<p>I agree, 690.12 should have exemptions for lower voltage, lower
power systems, and shorter runs; especially off grid. 10 years
ago, I was promoting some type of remote controlled disconnect at
the array, but that was for voltages over 400v, with unprotected
conduit runs over a 100 ft long, on systems over 10 kW. <br>
</p>
<p>For off grid where reliability is the number one safety issue,
we've gone back to pole mounts to avoid 690.12. If the
temperature goes below zero, and the customer is snow bound,
having the Rapid disconnect trip off is NOT creating a safer
situation. They need heat, unfrozen water supply, and
communications. Rural VFDs are not going to usually even get up
on the roof anyway. That's a scenario for in town, when they can
respond in less than 10 minutes. <br>
</p>
<p>Actually for residential systems in rural areas, the only person
that is going to get hurt on the roof is the customer trying to
reset the Rapid Disconnect, not the Fire Department. Maybe the
NEC task groups will finally see that fire fighter safety needs to
be balanced with the safety of the people they are trying to
protect. I hope that the NEC could reach this conclusion before an
untrained home owner breaks their neck. <br>
</p>
<pre class="moz-signature" cols="72">Ray Walters
Remote Solar
303 505-8760</pre>
<div class="moz-cite-prefix">On 4/29/20 10:17 AM,
<a class="moz-txt-link-abbreviated" href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a> wrote:<br>
</div>
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cite="mid:998baf393ede7d370a28b0fc76d99ce8@redwoodalliance.org">
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<p>Clearly, rapid shutdown increases cost and reduces reliability.
Given the excellent safety record of PV, prior to rapid shutdown
being required, it is unnecessary. The few anecdotal incidents
of PV fires were not enough to justify the requirement,
especially on smaller systems. </p>
<p>According to a friend who worked for a local installation
company that went under, a big part of the reason for their
failure was the chronic replacement of microinverters and
optimizers.</p>
<p>What steps can be taken to create some balance in the rapid
shutdown requirements that are in the NEC?</p>
<p><br>
</p>
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<p id="reply-intro">On 2020-04-29 07:27, Sky Sims wrote:</p>
<blockquote type="cite" style="padding: 0 0.4em; border-left:
#1010ff 2px solid; margin: 0">
<div id="replybody1">
<div dir="auto">So far rapid shutdown has been a nightmare.
It's added a lot of cost for no measurable benefit.
<div>Using always off devices like midnight solar and Tigo
makes it impossible to test open circuit voltages. Which
opens the door to tons of problems when commissioning
systems. </div>
<div>Also we've been trying out midnight Solar's product and
have had an absurd failure rate. Which means lots of truck
rolls and troubleshooting and system downtime. They send
replacement product but they aren't paying for the lost
weeks of productivity.</div>
<div>We have Tigo product in hand and are deciding which
project to try it on. But our big concern about using it
is not only the inability to confirm open circuit voltage
of the strings but also the way panels bypass if the
device doesn't allow the panel to connect properly. Both
of these features are a recipe for problems and potential
troubleshooting nightmares. The warranty from Tigo doesn't
cover our expense if the product fails. And that's really
what our reservations about the product boil down to right
now. If we're on a job with 50 units and one fails, the
contractor or the homeowner will be the ones eating the
expense of finding it and replacing it. There has to be a
better option. </div>
<div><br>
<div dir="ltr">Sky Sims
<div><a class="moz-txt-link-freetext" href="Https://EcologicalSystems.biz">Https://EcologicalSystems.biz</a></div>
</div>
<div dir="ltr"><br>
<blockquote type="cite" style="padding: 0 0.4em;
border-left: #1010ff 2px solid; margin: 0">On Apr 28,
2020, at 7:46 PM, Corey Shalanski
<a class="moz-txt-link-rfc2396E" href="mailto:coresolar@gmail.com"><coresolar@gmail.com></a> wrote:<br>
<br>
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<div dir="ltr">
<div dir="ltr">Now that 690.12 of the <em>NEC</em> 2017
has been in effect for several years, I am curious
how designers and installers are meeting the
associated requirements with string inverter-based
systems (*not* considering microinverters or DC
optimizers). I am generally a fan of the KISS
principle, and as best I can determine the <em>Tigo</em> TS4-F
device is one of the simplest options currently
available on the market. What are others finding?
<div> </div>
<div>I'd love to hear about favored options for
complying with rapid shutdown. Any success
stories? or better yet, any early failures?</div>
<div> </div>
<div>--</div>
<div>Corey Shalanski</div>
<div>Jah Light Solar</div>
<div>Portland, Jamaica</div>
</div>
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